Page 152 - Biology_F5

Comparative studies of natural groups of organisms

Reproduction in Dryopteris structure called prothallus. This forms a
haploid gametophyte generation, bearing
Task 3.9 male and female reproductive structures
Watch simulation or video showing (antheridia and archegonia), and rhizoids.
the life cycle of a fern plant. The archegonia produce female gametes

while the antheridia produce flagellated
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The diploid sporophyte generation have a male gametes, which swim to the archegonia
cluster of sporangia (sori) in which the spore in the presence of water to fertilise the egg,
mother cell undergoes meiotic division forming a zygote. The zygote develops
to produce haploid spores. When the to form a sporophyte generation with a
sporangia mature, they break and release the horizontal stem (rhizome) and leaves. The
spores. In favorable conditions, the spores gametophytes shrink and degenerate (Figure
germinate into a small green heart-shaped 3.25).

Prothalus
Spores Young
Meiosis
gametophyte Antheridium
Sporangium
Archegonium

Eggs
Zygote Sperm
Mature New sporophyte
sporophyte Fertilization
Young fern

Gametophyte

Figure 3.25: The life cycle of a fern plant (Dryopteris)

Adaptations of Dryopteris to its mode of (c) They have stomata that facilitate gas
life exchange.
Dryopteris possess the following features (d) They have xylem responsible for
which enable them to adapt to their transportation of water and dissolved
environment: minerals and also they have phloem

(a) They have chloroplasts containing for translocation of manufactured
chlorophyll for capturing light energy food.
needed for photosynthesis. (e) Rhizomes play part in storage food and

(b) They have roots for anchorage and propagation of new plants. Rhizomes
absorption of water and mineral salts. can remain viable in the soil for a long
time.

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